A scroll compressor is provided with a capacity modulation control, including a solenoid valve which can be moved to selectively control the supply of fluid to bypass valves to move the compressor between a full capacity and a reduced capacity position.
Scroll compressors are becoming widely utilized in refrigerant compression applications. In a scroll compressor, a pair of generally spiral wraps interfit to define compression chambers. One of the wraps is caused to orbit relative to the other, and as the two move, the size of the compression chamber is reduced, thereby compressing an entrapped refrigerant.
Under certain conditions, the capacity, or amount of refrigerant compressed by the compressor, may be desirably reduced. As an example, if the compressor is incorporated into an air conditioning system, and the cooling load is low, then it is more energy efficient to compress less refrigerant.
Various ways are known for reducing the capacity, including moving a valve to selectively open a passage to allow refrigerant to move from a partially compressed location back to suction. However, providing power to these valves has been somewhat challenging.
In particular, when electric valves such as solenoid valves have been utilized to provide capacity control within a scroll compressor, they have been mounted within a hermetically sealed compressor shell. Thus, the valves are exposed to the refrigerant circulating within the shell. The terminals that supply electric power to the valves must then have a hermetically sealed connection. In addition, since the valve is within the shell, it is somewhat difficult to cool the valve, or replace the valve.
It has been proposed to mount such a valve entirely outside of a shell. However, this requires communicating flow passages, which are outside of the shell also, and thus leads to some plumbing challenges.
In co-pending patent application Ser. No. 12/555,037, filed on Sep. 8, 2009, entitled “Scroll Compressor Capacity Modulation With Solenoid Mounted Outside a Compressor Shell,” the assignee of the present invention has disclosed and claimed a system wherein a solenoid control for capacity modulation is mounted outside a compressor shell, and has a mechanical component extending through the shell. While this system has great potential, it would be desirable to improve upon the system.